waku relay API: auto-subscribe

[D4nte]

Problem

Currently, developer always need to do a call to WakuRelay.subscribe() to use waku relay.

Solution

Similarly to nim-waku, an auto-subscribe to the default topic can make the API easier to use as the developer would have one less call to do.

[D4nte]

Let's wait until waku-org/nwaku#445 is resolved before trying to tackle this one as we know of some timing issues and there would be little value if we have various sleep in the library to allow for a resilient auto-subscribe.

[oskarth]

This is an issue more for library design, is that correct? In terms of making it ergonomic and having to setup fewer things for the default behavior.

[D4nte]

yes correct, I use the label 'API' to flag anything which is more about the API itself, the dev ex using it and any issue/improvements that can be done on its current design.

This is low priority as the focus is to get the chat app to support waku store first.